Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Wireless communications networks employ relay stations to increase the coverage and reliability of the wireless networks. The relay stations receive transmissions from a base station and retransmit the transmission to receivers, such as a wireless user. In establishing communications with the base station and relay station, the receiver establishes a communications channel with each station over which information is transmitted between the entities. As part of the process of establishing communications channels, the receiver “estimates” the communications channels to determine various parameters related to accurately extracting information from the received transmissions.
Channel estimation may be based at least in part on information provided to it by the respective transmitter, such as base station and relay station. For example, known pilot symbols may be included in the transmission of data symbols from the base station and relay station to the receiver, which uses the pilot symbols to estimate the communications channels. Typically, in a simple communications system having a base station, relay station, and receiver, there are three communications channels: a first communications channel between the base station and the receiver; a second communications channel between the base station and the relay station; and a third communications channel between the relay station and the receiver. The receiver performs channel estimation for communications channels with the base station and the relay station.